Re: [libvirt] [PATCHV2] qemu: ask for -enable-fips when FIPS is required

On a system that is enforcing FIPS, most libraries honor the current mode by default. Qemu, on the other hand, refused to honor FIPS mode unless you add the '-enable-fips' command line option; worse, this option is not discoverable via QMP, and is only present on binaries built for Linux. So, if we detect FIPS mode, then we unconditionally ask for FIPS; either qemu is new enough to have the option and then correctly cripple insecure VNC passwords, or it is so old that we are correctly avoiding a FIPS violation by preventing qemu from starting. Meanwhile, if we don't detect FIPS mode, then omitting the argument is safe whether the qemu has the option (but it would do nothing because FIPS is disabled) or whether qemu lacks the option (including in the case where we are not running on Linux). The testsuite was a bit interesting: we don't want our test to depend on whether it is being run in FIPS mode, so I had to tweak things to set the capability bit outside of our normal interaction with capability parsing. This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1035474 * src/qemu/qemu_capabilities.h (QEMU_CAPS_ENABLE_FIPS): New bit. * src/qemu/qemu_capabilities.c (virQEMUCapsInitQMP): Conditionally set capability according to detection of FIPS mode. * src/qemu/qemu_command.c (qemuBuildCommandLine): Use it. * tests/qemucapabilitiestest.c (testQemuCaps): Conditionally set capability to test expected output. * tests/qemucapabilitiesdata/caps_1.2.2-1.caps: Update list. * tests/qemucapabilitiesdata/caps_1.6.0-1.caps: Likewise. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- src/qemu/qemu_capabilities.c | 28 +++++++++++++++++++++++++++- src/qemu/qemu_capabilities.h | 1 + src/qemu/qemu_command.c | 2 ++ tests/qemucapabilitiesdata/caps_1.2.2-1.caps | 1 + tests/qemucapabilitiesdata/caps_1.6.0-1.caps | 1 + tests/qemucapabilitiestest.c | 20 +++++++++++++++----- 6 files changed, 47 insertions(+), 6 deletions(-) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 5e9c65e..9470814 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c

@@ -2630,6 +2631,31 @@ virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps, config.data.nix.path = monpath; config.data.nix.listen = false; + /* Qemu 1.2 and later have a binary flag -enable-fips that must be + * used for VNC auth to obey FIPS settings; but the flag only + * exists on Linux, and with no way to probe for it via QMP. Our + * solution: if FIPS mode is required, then unconditionally use + * the flag, regardless of qemu version, for the following matrix: + * + * old QEMU new QEMU + * FIPS enabled doesn't start VNC auth disabled + * FIPS disabled/missing VNC auth enabled VNC auth enabled + * + * Setting the flag here instead of in virQEMUCapsInitQMPMonitor + * or virQEMUCapsInitHelp also allows the testsuite to be + * independent of FIPS setting. + */ + if (virFileExists("/proc/sys/crypto/fips_enabled")) { + char buf[sizeof("1\n")];

+ char *ptr = buf;

+ + if (virFileReadAll("/proc/sys/crypto/fips_enabled", + sizeof(buf), &ptr) < 0) + goto cleanup; + if (*buf == '1')

+ virQEMUCapsSet(qemuCaps, QEMU_CAPS_ENABLE_FIPS); + } +

VIR_DEBUG("Try to get caps via QMP qemuCaps=%p", qemuCaps); /*